Example of Li pattern fitting: the case of the Lupus SFR. The left panel shows the case in which the age was determined using the $E{W}_{\text{Li}}^{\text{veil+Fe}}$, while the right panel shows the case in which the $E{W}_{\text{Li}}^{\text{Fe}}$ have been used. The solid black line represent the best-fit isochrone in the EW_Li vs. T_eff plane. The shaded region illustrates the model intrinsic dispersion at the best-fit age or its upper limit. The dashed black lines represent 95% upper and lower limits where no clear peak is observed. The blue dots show EW(Li) as a function of T_eff with the uncertainties on EW(Li) measurements. The text in the top-left corner on the plot shows maximum likelihood age.